The present invention relates to a programmable control system for controlling the temperature of the air available to the intake manifold of an engine.
The present invention is an improvement to the generally known class of thermocontrol systems utilized to control the temperature of the air input to an engine. These prior systems attempt to maintain the input air temperature at a single, fixed level such as 100.degree. F. (38.degree. C.) by utilizing a vacuum actuator located within an intake duct or tube of an air cleaner. Typically the air cleaner housing comprises a cold air inlet and a warm air inlet. The relative amount of cold or warm air permitted to enter the engine is controlled by a mixing valve which moves relative to these inlets under the control of engine vacuum. Engine vacuum is often modulated by a bi-metal temperature device situated within the air cleaner housing. When this type of device is incorporated within the smaller sized four cylinder engine, sufficient vacuum may not be available to adequately control the mixing valve under all operating conditions. A further deficiency of these prior systems is that the temperature is not matched to the variable engine conditions resulting in inefficiencies in operation.
In contrast the present invention provides for a flexible, programmable thermocontrol system for controlling the temperature of the air ingested by an engine and provides the flexibility for modifying the temperature profile in accordance with variations in engine load and other operating conditions. Accordingly the invention comprises:
An air temperature control system for an engine including an intake manifold, an air mixing housing in communication with the intake manifold. The housing includes a first inlet adapted to receive unheated air and a second inlet adapted to receive heated air and an air mixing valve movable in relation to the first and second inlets for controlling the relative quantity of heated and unheated air available to the intake manifold. The system further includes a control unit, responsive to at least one engine operating parameter and to the temperature of the air delivered to the intake manifold for generating an actuator control signal; and an actuator responsive to the actuator control signal that is mechanically linked to the movable air mixing valve for adjusting the air mixing valve in proportion to the actuator control signal. A temperature sensor located in the air cleaner housing is used to measure the temperature of the mixed air delivered to the intake manifold.